Your friends will post and share more information with you if you give them positive feedback by giving them a Good Share or adding a comment to their share. It's quick and easy to do, and it will help build traffic for your own shares.
Whenever you are viewing your friends' shares you'll see an "Add Comment" button at the top and bottom of the share. It looks like this:

Click on this button to add a text message comment on the share. Your comment will be added to the log of comments that's displayed at the bottom of the share (just scroll down to the bottom to see all the comments from visitors to this share). When a comment is added a Good Share is automatically added as well. Comments can be added to the Address, Discuss, Document, and Photo Blog applications.
To post a Good Share, scroll to either the top or the bottom of the share and you'll see:

Click on the ghosted check to give a Good Share to this share. It's your way of recommending this share to others, and letting the author know you liked the share. You'll see the Good Share check change to look like this:

Whenever this share is displayed, the total number of comments and Good Shares received are also displayed. KeepandShare users can use high numbers of comments and Good Shares to help guide them to popular content.
Good Shares may be added to Discussions, Documents and Photo Blogs.
Lastly, just below the comments area on the share, there is a list of all visitors who have given a Good Share vote on this share. The list looks like this:

If you've given a Good Share vote, you'll see your name here too to help build traffic to your share page. If you click on one of the names, it's a live link that will take you straight to the share page for that name. Visit some of these users and see what they're sharing. You might like their shares as well!
So you see, if you give Good Shares on a page, other KeepandShare users can discover your share page by clicking on you in this list.